Differential regulation of GLT-1/EAAT2 gene expression by NF-κB and N-myc in male mouse brain during postnatal development.

The synaptic glutamate level homeostasis is mainly maintained by the astrocytes membrane bound glutamate transporter type-1 (GLT-1/EAAT2). Alterations in its expression during development and aging and the underlying mechanisms are not well studied. Here, we report that NF-κB interaction was highest in both cerebral and cerebellar cortices at day 15 when compared with that at day 0 during development, and it further declined significantly in day 45, and remained unchanged in 20 and 70 weeks mice. On the other hand, N-myc interaction was highest at 0 day which significantly declined at 15-day and interestingly remained unaltered at later ages in both the cortices. This age dependent reciprocal pattern of NF-κB and N-myc interactions with their cognate GLT-1 promoter sequences was further correlated with GLT-1 protein and transcript levels. We found that higher NF-κB interaction with its cognate GLT-1 promoter sequences correlates with up-regulation whereas the higher N-myc interaction correlates with down-regulation of GLT-1 expression during postnatal developmental age up to 15 day, however, such phenomenon was not found in the higher ages from day 45 to 70 weeks. Thus our data suggests a postnatal development- and age dependent differential interaction of transcription factors NF-κB and N-myc to their respective sequences and they act as positive and negative regulator, respectively of GLT-1 gene expression in the brain during early developmental period in both cerebral and cerebellar cortices which might be different in aging of mice.